Doors used as replacements or for new construction are conventionally produced of sheet metal. When these doors are used as outside entrances, as distinguished from interior doors, it is desirable to have one or more window sections, referred to as lights, formed in the door. Numerous frame assemblies have been proposed for use as door light frames.
These frames comprise inner and outer half-frames which sandwich a translucent panel therebetween and support the panel within an opening formed in the door. Each half-frame is formed separately and has a plurality of side members defining a closed polygon. Usually, the side members of each half-frame are separately formed and then attached together by welding, for example U.S. Pat. No. 3,004,641 to Johnson, or by corner attaching members, for example, U.S. Pat. No. 4,024,691 to Hansen et al and U.S. Pat. No. 3,949,526 to Sherlock et al. These conventional methods of forming the half-frames are difficult, time-consuming and expensive. Additionally, these frames are relatively weak at their side member connections.
Another disadvantage of conventional door frame systems is that they often employ differently formed members for the inner half-frame and the outer half-frame. The use of two different half-frames to form each frame assembly significantly increases manufacturing and assembly costs.
Numerous types of fasteners have been used to secure the half-frames together and to the door. Such arrangements have included threaded fasteners (e.g., French Pat. No. 544,753, U.S. Pat. No. 1,171,444 to Larson et al, and U.S. Pat. No. 3,969,857 to Stark), externally threaded fasteners on one half-frame and internally threaded bores on the mating half-frame (e.g., U.S. Pat. No. 4,128,977 to Schubeis), and mating pin and bore arrangements (e.g., U.S. Pat. No. 3,760,543 to McAllister). These arrangements are disadvantageous since they are difficult to manufacture and assemble, and since they do not provide adequate thermal insulation between the inner and outer half-frames. The thermal insulation problem is particularly significant for metal frames coupled directly by metal fasteners which readily conduct heat between the inner and outer half-frames.